Increased beam output and dynamic field shaping for radiotherapy system

Abstract

Systems and methods provide a radiotherapy treatment by focusing an electron beam on an x-ray target (e.g., a tungsten plate) to produce a high-yield x-ray output with improved field shaping. A modified electron beam spatial distribution is employed to scan the x-ray target, such as a 2D periodic beam path, which advantageously lowers the temperature of the x-ray target compared to typical compact beam spatial distribution. As a result, the x-ray target can produce a high yield x-ray output without sacrificing the life span of the x-ray target. The use of a 2D periodic beam path allows a much colder x-ray target functioning regime such that more dosage can be applied in a short period of time compared to existing techniques.

What is claimed is: 
     
       1. A radiotherapy treatment system, comprising:
 an electron emission device configured to produce and emit an electron beam; 
 a plurality of steering coils coupled to said electron emission device, and configured to produce magnetic fields in perpendicular directions for steering said electron beam; and 
 a device disposed to intersect said electron beam downstream of said plurality of steering coils, wherein said plurality of steering coils are controlled to scan said electron beam in a two-dimensional (2D) periodic path, and produce a distribution of electrons across a surface of said device. 
 
     
     
       2. The radiotherapy treatment system of  claim 1 , wherein said device comprises a field shaping device configured to shape said distribution of electrons according to a shape of a target volume in a patient. 
     
     
       3. The radiotherapy treatment system of  claim 1 , wherein said device comprises a target device operable for generating an x-ray beam responsive to an interaction with said distribution of electrons to produce a distribution of x-rays. 
     
     
       4. The radiotherapy treatment system of  claim 3 , further comprising a field shaping device disposed downstream of said target device and configured to shape said distribution of x-rays according to a shape of a target volume in a patient. 
     
     
       5. The radiotherapy treatment system of  claim 1 , wherein said electron emission device comprises:
 an electron gun assembly; and 
 a linear accelerator coupled to receive electrons from said electron gun assembly, and operable to produce said electron beam emitted from said electron emission device. 
 
     
     
       6. The radiotherapy treatment system of  claim 1 , wherein said 2D periodic path comprises a Lissajous-type shape. 
     
     
       7. The radiotherapy treatment system of  claim 1 , wherein said 2D periodic path comprises a spherical harmonic-based shape. 
     
     
       8. The radiotherapy treatment system of  claim 1 , wherein said 2D periodic path comprises a linear combination of an s-wave shape, a p-wave shape, and a d-wave shape. 
     
     
       9. The radiotherapy treatment system of  claim 1 , wherein said 2D periodic path comprises a non-Cartesian shape. 
     
     
       10. The radiotherapy treatment system of  claim 1 , wherein said 2D periodic path comprises a convex hull. 
     
     
       11. The radiotherapy treatment system of  claim 1 , further comprising a control device coupled to said plurality of steering coils, and operable to control said plurality of steering coils to cause said electron beam to scan in said 2D periodic path. 
     
     
       12. The radiotherapy treatment system of  claim 1 , wherein said electron beam is of a range from one MeV to 300 MeV. 
     
     
       13. In a radiotherapy treatment system, a method comprising:
 generating and emitting an electron beam using an electron emission device; 
 producing, with a plurality of steering coils, magnetic fields in perpendicular directions for steering said electron beam; and 
 controlling said plurality of steering coils to scan said electron beam in a two-dimensional (2D) periodic path across a surface of a device downstream of said plurality of steering coils, thus producing a distribution of electrons. 
 
     
     
       14. The method of  claim 13 , further comprising shaping said distribution of electrons with said device according to a shape of a target volume in a patient. 
     
     
       15. The method of  claim 13 , further comprising generating an x-ray beam responsive to an interaction of said distribution of electrons with said device, thus producing a distribution of x-rays. 
     
     
       16. The method of  claim 15 , further comprising shaping said distribution of x-rays with a second device disposed between said device and a target volume, and according to a shape of said target volume. 
     
     
       17. The method of  claim 13 , wherein said 2D periodic path has a shape selected from a group consisting of: a Lissajous-type shape; a spherical harmonic-based shape; a linear combination of an s-wave shape, a p-wave shape, and a d-wave shape; a non-Cartesian shape; and a convex hull. 
     
     
       18. The method of  claim 13 , wherein said controlling comprises adjusting at least one of a voltage and a current applied to said plurality of steering coils. 
     
     
       19. The method of  claim 13 , further comprising:
 selecting a plurality of shapes for said 2D periodic path; and 
 assigning weights to said plurality of shapes, wherein each weight of said weights indicates a beam intensity for a respective shape of said plurality of shapes; 
 wherein said controlling comprises:
 generating control signals representing said plurality of shapes and said weights; and 
 adjusting at least one of a voltage and a current applied to said plurality of steering coils according to said control signals. 
 
 
     
     
       20. The method of  claim 13 , wherein said electron beam is of a range from one MeV to 300 MeV.